1. Field of the Invention
The present invention relates in general to power switches and in particular to a new and useful gas-blast power switch which includes means for directing a flow of arc quenching gas transversely across an arc produced between contacts of the switch.
2. Description of the Prior Art
In power switches, a common problem is the formation of an electric arc between a fixed contact of the switch and a movable contact which is moved away from the switch in order to open the switch. Known power switches include means for removing energy from the arc in order to extinguish it which comprise driving the arc in a rotational direction in the presence of a pressurized gas which is usually sulphur hexafluoride (SF.sub.6). In this way it is possible to extinguish the arc at the zero passage. In a prior art switching device of this kind (ELEKTRIE, No. 10, 1967, page 364) the electrodes contact each other in the "switch on" or closed position. To turn the switch to its "switch off" or open position, the inner electrode which forms a cylindrical contact is brought into a concentric position relative to the outer contact which forms an annular contact. An annular gap is thereby formed between the two contacts and an arc formed in this annular gap is driven into a rotational motion by a coaxial blowout coil which is permanently provided in the circuit up to the time the arc is extinguished.
Another prior art switch, (German Offenlegungsshrift No. 43 49 193) comprises two chambers of unequal volume. A rotating auxiliary arc is drawn in the smaller chamber during this connection of the switch for the purpose of producing pressure in a gas contained in the smaller chamber. Heated gas from the small chamber is then displaced through a nozzle made of insulating material and into the larger chamber. An arc extinction is thereby effected in a well-known manner by a gas jet from the nozzle. No blowout coil is provided in this structure.